Field
This invention relates generally to an unmanned aerial vehicle (UAV) that includes a ducted propulsion fan and, more particularly, to a UAV that includes a collapsible ducted propulsion fan provided in a stowed configuration for launch or transport and then deployed to a flight configuration after launch or for lift off.
Discussion
UAVs are known in the art that can be remotely controlled during flight or be controlled by an onboard control system that has been pre-programmed. UAVs have many applications including military applications, such as for surveillance, reconnaissance, target accusation, etc., and civilian applications, such as for data gathering during natural disasters. Depending on the application, a UAV can be equipped with many and various payloads, such as detectors, sensors, cameras, communications devices, munitions, etc. UAVs are typically launched from various platforms, such as ground platforms, other aircraft, ships, etc.
UAVs typically have one or more rotor systems that may be driven by various types of propulsion systems, such as internal combustion engines, electric drive motors, gas turbine engines, etc. Some UAVs have propulsion systems that employ a ducted fan that provides various advantages such as reduced power for a particular thrust, the opportunity for lower acoustic emissions, operational safety, etc. The efficiency of thrust generation increases rapidly with an increase in the diameter of the duct. However, providing ducted fans on UAVs has the disadvantage that the duct is relatively large and bulky, and as such is limited in its ability to be transported in large numbers and they must be launched in their flight configuration, which precludes launch of the vehicle in, for example, a small-diameter launch tube.
Many types of ducted fan UAVs are vertical takeoff and landing (VTOL) vehicles that takeoff from the ground, ships, etc., where they fly to perform their mission in both a vertical and lateral direction. However, it may be desired to carry multiple UAVs on a single platform, such as an aircraft or a ship, where it would be desirable to conserve space by providing the UAVs in a collapsed and stowed configuration to later be deployed prior to launch or in the air after being launched. Thus, a need exists to provide a reliably collapsible and deployable ducted fan UAV, where duct diameters several times the length of the vehicle may be possible.